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<h3><a name="SECTION00161415000000000000000"></a><a name="ctypes-calling-functions-continued"></a>
<br>
14.14.1.5 Calling functions, continued
</h3>

<p>
Note that printf prints to the real standard output channel, <em>not</em> to
<code>sys.stdout</code>, so these examples will only work at the console
prompt, not from within <em>IDLE</em> or <em>PythonWin</em>:
<div class="verbatim"><pre>
&gt;&gt;&gt; printf = libc.printf
&gt;&gt;&gt; printf("Hello, %s\n", "World!")
Hello, World!
14
&gt;&gt;&gt; printf("Hello, %S", u"World!")
Hello, World!
13
&gt;&gt;&gt; printf("%d bottles of beer\n", 42)
42 bottles of beer
19
&gt;&gt;&gt; printf("%f bottles of beer\n", 42.5)
Traceback (most recent call last):
  File "&lt;stdin&gt;", line 1, in ?
ArgumentError: argument 2: exceptions.TypeError: Don't know how to convert parameter 2
&gt;&gt;&gt;
</pre></div>

<p>
As has been mentioned before, all Python types except integers,
strings, and unicode strings have to be wrapped in their corresponding
<code>ctypes</code> type, so that they can be converted to the required C data
type:
<div class="verbatim"><pre>
&gt;&gt;&gt; printf("An int %d, a double %f\n", 1234, c_double(3.14))
Integer 1234, double 3.1400001049
31
&gt;&gt;&gt;
</pre></div>

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